Taeniid Infections Research Articles

Management to Reduce Impact of Cerebral Coenurosis in Bonga Sheep in Kafa Zone, South Western Ethiopia

Coenurosis, a parasitic and fatal disease, is widespread in the highlands of Ethiopia where 75% of the country’s sheep population are found. There is significant prevalence of the disease in the current study area. Therefore, the current study was conducted with the objectives to reduce impact of cerebral coenurosis in sheep production in the study area through integrating different prevention and control options and to raise the community awareness about disease. Questionnaire surveys, coproscopic examination of dog faeces and household level surveillance was used to collect data on reported coenurosis cases and taeniid infections. Awareness creation trainings and regular deworming of dogs were used as an intervention to reduce the prevalence of the disease. A total of 107, 134, 153, and 124 dogs were dewormed during the first, second, third, and fourth rounds during the study period respectively. Eggs were detected in 58.53% (95% CI: 47.4- 68.86) of pre-deworming fecal samples of dogs. Eggs were detected in 24.18% (95% CI: 40.0–49.7) of post-intervention fecal samples, 34.35% less than pre-intervention. At the beginning of the intervention the level of awareness of the farmers in the intervention sites about the cause of the disease was 12.2% which was increased to 51.03% at the end of the intervention. The community-based integrated animal health management approach for the control of coenurosis has the potential to be scaled-up across the country, thereby reducing economic losses of communities where the disease is endemic.

A survey of gastrointestinal parasites in dogs illegally entering the UK (2015-2017).

This study involving non-compliant, seized dogs entering the UK surveyed endoparasites detected in faecal samples. A focus was placed on taeniid infection as the detection of these tapeworms acts as a marker for failure of effective tapeworm treatment. Individual faecal samples taken from 65 dogs over a 24-month period were examined for helminth eggs, for protozoal oocysts and cysts, using a centrifugal flotation technique. Any sample presenting positive results for taeniid eggs had residual faeces examined using polymerase chain reaction to aid speciation of the tapeworm eggs. Additionally, a Baermann technique was used to assess faeces for lungworm larvae. Patent endoparasite infection was detected in 27.7% of dog faecal samples. No sample was positive for lungworm larvae. Five dogs were co-infected with Isospora spp. and Toxocara canis. One dog sample was detected with taeniid eggs, identified as Taenia serialis. The taeniid-positive dog indicated that appropriate tapeworm treatment may not have occurred, reinforcing the risk to the UK of illegally imported dogs potentially introducing Echinococcus multilocularis infection.

Taenia multiceps in Northern Tanzania: An Important but Preventable Disease Problem in Pastoral and Agropastoral Farming Systems

Coenurosis due to Taenia multiceps has emerged as a major concern to small ruminant-owning communities in northern Tanzania. Although a high incidence of disease has been reported, gaps still remain in our knowledge of the disease problem across different agro-ecological settings. The study aimed to determine the prevalence of coenurosis in small ruminants and taeniid infection in dogs and identify risk factors for infection. Questionnaire surveys, postmortem examination of small ruminants, and coproscopic examination of dog faeces were used to collect data on reported coenurosis cases and taeniid infections, respectively. The twelve-month period prevalence of coenurosis in small ruminants was 8.4% (95% CI 8.2–8.6). The prevalence of taeniid infection in dogs was 12.5% (95% CI 9.1–17.4). The village-level prevalence of coenurosis in sheep and goats was significantly correlated with taeniid infection prevalence in dogs (r = 0.51, p = 0.029). Multivariable analysis indicated that home slaughter was significantly associated with the livestock owner-reported neurological syndrome due to coenurosis in sheep and goats (OR = 13.3, 95% CI 4.2–42.0, p < 0.001) and the practice of offering discarded brains to dogs was significantly associated with taeniid infection prevalence in dogs (OR = 2.80, 95% CI 0.98–7.98, p = 0.05). Coenurosis is a major disease problem in livestock-keeping communities of northern Tanzania, but there is little awareness of transmission risks associated with home slaughter and dog feeding practices. There is a need for veterinary and animal health services to engage more actively with communities to increase awareness of the transmission cycle of T. multiceps and the preventive measures that can be taken to reduce the impact of disease in livestock-dependent communities.

Prevalence and factors associated with taeniid infection among owned dogs in Ibadan, Oyo State, Nigeria

Human association with taeniid infected dogs could pose risk of infection. Few studies exist on prevalence of taeniid infections in dogs in Nigeria, however, none have attempted to determine extrinsic factors associated with the prevalence among owned dogs. This study, therefore, aimed at determining taeniid infection and its associated intrinsic and extrinsic factors among owned dogs in Ibadan, Oyo State, Nigeria. A cross sectional study involving the screening of 185 dog faecal samples using the floatation method was done. Questionnaire was used to obtain data on intrinsic factors such as age, gender, breed; and extrinsic factors such as management and hygienic practices and environmental factors from participating dog owners. Data obtained were analysed using descriptive statistics and Fisher's exact test at α0.05. The mean age of the respondents was 35.7 ± 11.3 years, while the median age of the dogs was 20 months (Interquartile range 10.5 – 40). The prevalence of taeniid infection was 4.87%. Extrinsic factors such as the water source – tap water (Odds Ratio (OR): 5.5; 95% Confidence Interval (CI): 1.01, 36.8) and the feed types – dry foods (OR: 11.4; 95% CI: 1.1, 159.3) were significantly associated with taeniid infection. None of the intrinsic factors was significantly associated with taeniid infection. Taeniid infection is low among owned dogs in the study area. Source of water and the food type to dogs could be possible source of taeniid infection to dogs. Proper dog deworming and provision of clean water source could help reduce taeniid infection in dogs.

Copro-polymerase chain reaction has higher sensitivity compared to centrifugal fecal flotation in the diagnosis of taeniid cestodes, especially Echinococcus spp, in canids

Prompt and reliable diagnostic tests for taeniid infection in canids are important due to the risk of zoonoses like Echinococcus spp. Current diagnostic methods relying on fecal flotation lack sensitivity and specificity, but this has rarely been quantified due to the challenges in performing adult cestode recovery (the gold standard) in domestic dogs (Canis familiaris). Therefore, we recovered adult Taenia and Echinococcus spp. from intestines, as well as fecal/intestinal material from 484 wild canids trapped for fur in two Canadian provinces (276 foxes – primarily Vulpes vulpes, coyotes – Canis latrans, and wolves – Canis lupus in Québec and 208 coyotes in Saskatchewan). The performances of a newly developed coproPCR for tapeworm DNA detection in dogs, and centrifugal fecal flotation using Sheather’s solution, were evaluated against adult cestode recovery. Overall, adult taeniid cestode prevalence (Taenia and/or Echinococcus) was 28 % (95 % CI: 23–33 %) in Québec (62 % (CI: 51−73%) of 74 coyotes, 65 % (CI: 44−82) of 23 wolves, and 11 % (CI: 7−16%) of 179 foxes) and 79 % (CI: 73−84%) of 208 coyotes in Saskatchewan. In Québec, E. canadensis and Taenia spp. were detected in coyotes and wolves, and foxes were only infected with Taenia spp., whereas Saskatchewan coyotes were predominantly infected with E. multilocularis (at significantly higher prevalence, but not intensity, than coyotes in Québec). Compared with centrifugal fecal flotation, the new coproPCR had at least double the sensitivity (58 % vs 23 % in QC coyotes, 57 % vs 23 % in QC wolves, 24 % vs 0% in QC foxes, and 80 % vs 25 % in SK coyotes). Notably, no taeniid eggs were detected on flotations from foxes infected with Taenia spp., and the new coproPCR had highest sensitivity in Saskatchewan coyotes, which were predominantly infected with E. multilocularis. CoproPCR has promising prospects for use in Veterinary clinics and diagnostic laboratories to detect taeniid cestode infections because of its higher sensitivity than faecal flotation methods. This is particularly important for zoonotic Echinococcus spp. where, from a public health perspective, false negatives are a much greater concern than false positives.

Granulomatous responses in larval taeniid infections.

Granulomas are responses to persistent nonliving bodies or pathogens, centrally featuring specialized macrophage forms called epithelioid and multinucleated giant cells. The larval stages of the cestode parasites of the Taeniidae family (Taenia, Echinococcus) develop for years in fixed tissue sites in mammals. In consequence, they are targets of granulomatous responses. The information on tissue responses to larval taeniids is fragmented among host and parasite species and scattered over many decades. We attempt to draw an integrated picture of these responses in solid tissues. The intensity of inflammation around live parasites spans a spectrum from minimal to high, parasite vitality correlating with low inflammation. The low end of the inflammatory spectrum features collagen capsules proximal to the parasites and moderate distal infiltration. The middle of the spectrum is dominated by classical granulomatous responses, whereas the high end features massive eosinophil invasions. Across the range of parasite species, much observational evidence suggests that eosinophils are highly effective at killing larval taeniids in solid tissues, before and during chronic granulomatous responses. The evidence available also suggests that these parasites are adapted to inhibit host granulomatous responses, in part through the exacerbation of host regulatory mechanisms including regulatory T cells and TGF-β.

The impact of socio-cultural factors on transmission of Taenia spp. and Echinococcus granulosus in Kosovo.

Echinococcus granulosus sensu latu (s.l.) and Taenia hydatigena are common parasites of ruminant intermediate hosts in the Balkans. Transmission is linked mainly to home slaughtering and the feeding of infected organs to dogs. In Kosovo, many old sheep are slaughtered particularly during Eid al-Adha (Feast of Sacrifice). To determine whether this tradition could affect parasite transmission, we compared the probability of 504 dogs to contract taenid infections after deworming during one period before Eid al-Adha and a similar period beginning with this event. Initially, taeniid eggs were detected in 6·2% (CI 4·2-8·6) of the dogs. The prevalence before Eid al-Adha was significantly lower (1·2%, CI 0·4-2·6) as compared with the prevalence after the event (4·3%, CI 2·6-6·3). A comparable trend was apparent at species level for T. hydatigena and E. granulosus. These results indicate that the pronounced increase of taeniid infections, including E. granulosus s.l., after Eid al-Adha is linked to traditional home slaughtering that occurs during this celebration. This particular epidemiological situation provides an opportunity for implementing focussed control activities.

Sero-prevalence of Taenia spp. infections in cattle and pigs in rural farming communities in Free State and Gauteng provinces, South Africa

The aim of this study was to determine sero-prevalence of bovine and porcine cysticercosis in cattle and pigs in rural farming communities in Free State and Gauteng Provinces, Republic of South Africa. Blood samples were collected for a period of twelve months from live cattle (n=1315; 1159) and pigs (n=436; 240) and the serum extracted and stored before analysis by a monoclonal antibody based (HP10) antigen detection ELISA.Results revealed a generally high sero-prevalence and wide distribution throughout the two provinces with Free State having a higher sero-prevalence in both cattle and pigs (23% and 34%) than Gauteng province (15% and 14%). Consumption of infected meat that is either not inspected/missed at meat inspection; poor livestock management practices and limited sanitation in rural communities might have contributed to the occurrence of Taenia spp. infections in the two provinces. It is therefore, recommended that cysticercosis status of animals be established before slaughter. This would assist in ensuring that infected animals are not slaughtered for human consumption or zoonosis preventive measures are taken. Furthermore, public awareness programs on life cycles of T. saginata, T. solium and T. hydatigena and the use of more sensitive diagnostic tools are recommended as part of effective control strategies against taeniid infections.

Development of LAMP assays for the molecular detection of taeniid infection in canine in Tibetan rural area.

For field-identification of taeniid cestodes in canine animals in Tibetan area, loop-mediated isothermal amplification (LAMP) assays for Echinococcus multilocularis, E. shiquicus, Taenia hydatigena, T. multiceps, T. pisiformis and T. crassiceps were developed and evaluated along with the reported assay for E. granulosus. The LAMP assays showed specific reaction with their corresponding target species DNA with the detection limit of 1 to 10 pg. Moreover, the assays for E. granulosus, E. multilocularis, T. hydatigena and T. multiceps could detect DNA extracted from 3 or more eggs of their corresponding target species. Then, the LAMP assays were applied on samples containing 3 to 35 taeniid eggs obtained from 61 field-collected canine feces in Qinghai, and the result was compared with a reported multiplex PCR and sequence analysis. The LAMP assays and the PCR detected single species DNA of E. granulosus, E. shiquicus, T. hydatigena and T. multiceps in 5, 2, 44 and 2 samples, respectively. In the rest 8 samples, DNA of both E. granulosus and T. hydatigena were detected by the PCR but the LAMP assays detected those DNAs in 2 samples and only T. hydatigena DNA in 6 samples. It was assumed that less than 3 E. granulosus eggs were mixed in the samples although the samples contained 21 to 27 eggs in total. In conclusion, the LAMP assays were less sensitive than the multiplex PCR, but would have adequate sensitivity for field use in Tibetan area.

Molecular detection of Taenia spp. in dogs' feces in Zanjan Province, Northwest of Iran.

Aim:Echinococcus and Taenia spp. are important but neglected zoonotic helminths of dogs. Dogs as the most relevant definitive hosts harbor several species of Taenia and Echinococcus simultaneously in their gastrointestinal lumen which are morphologically indistinguishable. In this study, we used a multiplex polymerase chain reaction (PCR) method to identify Taeniid infections which seem to be highly distributed in the study region.Materials and Methods:A total of 450 dog fecal samples were collected from eight different areas of Zanjan province, northwest of Iran, and examined using a flotation method followed by multiplex PCR for detection and identification of parasites’ eggs.Results:Gastrointestinal parasites were found in 86 out of 450 fecal samples (19.1%) by microscopic examination. Taeniid eggs were observed in 5.6% of samples, containing 0.45%, 3.8%, and 1.3% Echinococcus granulosus, Taenia spp., and mix infection of both E. granulosus and Taenia spp., respectively. Echinococcus multilocularis was absent in the samples.Conclusion:A relatively low rate of E. granulosus (1.8%) was observed in this study. However, risks of this parasite should not be overlooked, and control programs need to be extended for this species and other Taeniid spp. In particular, dogs are recommended to be dewormed more frequently.

Prevalence and risk factors of Echinococcus granulosus infection in dogs in Moroto and Bukedea districts in Uganda.

A cross sectional study was conducted in Moroto and Bukedea districts of Uganda from May to September 2013 to determine the prevalence and risk factors of Echinococcus granulosus infection in dogs. Fresh dog faecal samples were collected, preserved in 70% ethanol, and later screened for presence of taeniid eggs using zinc chloride floatation method. Positive samples were confirmed by a copro-PCR (polymerase chain reaction) for E. granulosus using NADH dehydrogenase sub-unit 1 gene (NADH1) as a target molecular marker. Structured questionnaires and focus group discussions were used to collect quantitative and qualitative data for risk factor identification. Study sub-counties were selected by simple random sampling. Overall apparent prevalence of taeniid infection in dogs of 14.9% (39/261, confidence interval 10.6-19.2) in both districts was recorded using the faecal floatation test. The sensitivity of the faecal floatation test was found to be 78% (25/32), while the specificity was 93% (215/229). Copro-PCR results revealed a true prevalence of 14.4% (9.91-19.0, 95% CI) in dogs in Moroto district and 7.4% (2.14-12.60, 95% CI) in Bukedea district. The overall true prevalence of cystic echinococcosis (CE) was 12.2% (8.70-15.76, 95% CI) in both districts. The major risk factors identified using logistic regression were uncontrolled access of dogs to animal slaughter facilities, higher cattle herd sizes and lack of knowledge about the disease. It was recommended that restricting dog access to infected tissues and public health education about epidemiology of CE should be done.

The occurrence of taeniids of wolves in Liguria (northern Italy).

Canids are definitive hosts of Taenia and Echinococcus species, which infect a variety of mammals as intermediate or accidental hosts including humans. Parasite transmission is based on domestic, semi-domestic and wildlife cycles; however, little is known of the epidemiological significance of wild large definitive hosts such as the wolf. In this study, 179 scats of wolves (Canis lupus italicus) collected throughout the Italian region of Liguria were analyzed for the detection of taeniid infection. Taeniid egg isolation was performed using a sieving/flotation technique, and the species level was identified by PCR (gene target: 12S rRNA and nad 1) followed by sequence analyses. Based on sequence homologies of ≥99%, Taenia hydatigena was identified in 19.6%, Taenia krabbei in 4.5%, Taenia ovis in 2.2%, Taenia crassiceps in 0.6%, Hydatigera taeniaeformis in 0.6% and Echinococcus granulosus in 5.6% of the samples. According to these results, Canis lupus italicus can be considered as involved in the wild (including cervids and rodents) and semi-domestic cycles (including sheep and goats) of taeniids in this area.

Echinococcus multilocularis infections in dogs from urban and peri-urban areas in France

Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a severe zoonotic disease. It is maintained through a sylvatic life cycle based on predator-prey interactions mainly between foxes and rodents. Dogs are also good definitive hosts; and due to their close proximity to humans, they may represent a major risk factor for the occurrence of human cases. In two medium-sized cities of Eastern France (Annemasse and Pontarlier), located in highly endemic areas, 817 dog feces samples were collected and analyzed by a flotation technique followed by a multiplex PCR assay. For the first time in France, we assessed the presence of E. multilocularis DNA in four dog feces samples, in which it represents an estimated prevalence of 0.5% (95% CI; 0.1% <> 1.3%). Eight other samples presented taeniid infections from three different species (Taenia crassiceps, Taenia serialis, and Taenia polyacantha). When considering both E. multilocularis and Taenia sensu lato, prevalence rose to 0.6% in Annemasse and 2.6% in Pontarlier. In this highly endemic context, proper application of the usual deworming recommendations (70% of the dogs were treated twice a year or more) failed to prevent dog infection, particularly for hunting dogs. Our results stressed the need to adapt treatment to the environmental context and to the specific activity of dogs. Further epidemiological surveys in domestic dogs and cats using this coprological approach are still needed to obtain a better overview of infection and the associated zoonotic risk.

Epidemiological Study and Control Trial of Taeniid Cestode Infection in Farm Dogs in Qinghai Province, China

ABSTRACTAn epidemiological study and control trial were conducted to assess taeniid infection in farm dogs in Qinghai Province, China. To improve egg detection by fecal examination, a deworming step with praziquantel was incorporated into the sampling methodology. As a result, a marked increase in the number of egg-positive samples was observed in samples collected at 24 hr after deworming. Then, the fecal examination and barcoding of egg DNA were performed to assess the prevalence of taeniid species in dogs from Xinghai, Haiyan, Gangcha and Chengduo counties. Analysis of 277 dog feces revealed that taeniid cestodes, including Taenia spp. and Echinococcus granulosus, were highly prevalent in Xinghai (34.4%), but eggs were not found in Haiyan where a control trial on canine echinococcosis had been conducted 20 years previously. A control trial involving the administration of 5–10 mg/kg praziquantel to 90 farm dogs at 45-day intervals was conducted in Xinghai. The prevalence of taeniid cestodes in the dogs was reduced to 9.6% and 4.9% after one and two years, respectively, indicating that some dogs were not administered praziquantel properly. A questionnaire survey of farmers in Xinghai and Haiyan revealed that most farmers in Xinghai were not familiar with echinococcosis or the transmission route of the disease, while most farmers in Haiyan had a more thorough understanding of the disease. The findings implied that a program for educating local farmers would be important for efficiently controlling canine taeniid infection in the region.

Morphological and molecular analyses of larval taeniid species in small mammals from contrasting habitats in Denmark

Taeniid infections in intermediate hosts manifest themselves as extraintestinal larval stages which, in early development, lack species-specific characteristics. The inability to distinguish infections of zoonotic importance such as Echinococcus multilocularis from other taeniid infections that have mainly veterinary significance stimulated the development of species-specific molecular diagnostics. In this study, the prevalence of taeniid infections in potential intermediate hosts was evaluated using both morphological diagnosis and a newly described multiplex polymerase chain reaction (PCR) for species determination. Small mammals (N=719) were trapped in three different types of habitats in north-east Zealand, Denmark. The sensitivity of the multiplex PCR (90.5%) exceeded that of morphological examination (57.9%) for identifying 95 taeniid infections. The use of the multiplex PCR resulted in higher prevalence rates due to improved detection of immature liver infections with Hydatigera taeniaeformis and Versteria mustelae, but did not affect the observed prevalence rates of peritoneal metacestodes of Taenia polyacantha. The prevalence of taeniid infections showed a significant difference according to habitat type, potentially identifying a 'sylvatic' transmission and an 'urban' transmission, with marked variation among different taeniid species. Versteria mustelae and T. polyacantha were more prevalent in rural forests, while infections with H. taeniaeformis were dominant in urban parks/forests and in residential and farm gardens. The multiplex PCR facilitated a better utilization of wildlife samples by yielding a higher number of definitive diagnoses of ambiguous taeniid infections in liver lesions, allowing for more accurate epidemiological data and, hence, a more accurate risk assessment.

Parasitic infections of domestic cats, Felis catus, in western Hungary

During 2011, faeces from 235 owned domestic cats from a rural area in western Hungary were examined using standard coproscopical techniques. The overall prevalence of cats with endoparasites was 39.6% (95% CI 33.3–46.1). The most frequently identified faecal forms were those of ascarids (Toxocara, 17.4%; Toxascaris 7.2%), followed by those of Aelurostrongylus lungworms (14.5%), hookworms (11.1%), taeniid cestodes (4.7%), Cystoisospora coccidians (4.3%), and capillarids (3.8%). Single and multiple infections with up to five parasites concurrently were founded in 24.7% and 14.9% of the cats, respectively. Mixed endoparasite infections were recorded more frequently (p=0.0245) in cats greater than one year old compared to younger cats. Young cats (≤1 year) were parasitized more frequently (p<0.05) with ascarids and Cystoisospora spp. but demonstrated infections of hookworms, lungworms and taeniid cestodes less often than the older cats. Cats with taeniid infection were more likely (p<0.05) to harbour Toxocara, hookworm, Aelurostrongylus, and capillarid infections than cats without taeniid cestodes. Cats of owners who claimed the use of wormers were less frequently helminth-positive compared to cats whose owners did not use anthelmintics (21.2% vs. 44.4%; p=0.001).A subset of 115 faecal samples screened by a coproantigen ELISA revealed Giardia-specific antigen in 37.4% samples. Giardia cysts were found by immunofluorescent staining in 30 of the 43 samples tested positive for Giardia by ELISA.In addition, ectoparasites collected from 82 cats by body search and combing were identified. Fleas (1–30 per cat), biting lice (Felicola subrostratus), and ticks (1–5 per cat) were isolated from 58, 1 and 43 cats, respectively. Ctenocephalides felis was identified on all flea infested cats while single specimens of C. canis and Pulex irritans were recovered from three and two cats, respectively. All but one tick collected were adult Ixodes ricinus; the single other tick was a nymph of I. canisuga.By providing basic data on the epidemiology of parasitic infections, the results of this survey should emphasize the need of attending to parasites of cats from the veterinary point of view with respect to both appropriate diagnostics and control.

Acute coenurosis of dairy sheep from 11 flocks in Greece

CASE HISTORY: A syndrome of acute neurological dysfunction with increased mortality was observed in lambs of 10 dairy sheep flocks and adult animals in one flock in Central and Northern Greece. Each farmer completed a questionnaire regarding the management and feeding of their flocks. In seven of the 11 flocks the affected animals were grazing pasture, while in the remaining four flocks (5, 8, 9, 10) the animals were fed alfalfa hay (Medicago sativa) and concentrates indoors. A follow-up study of the affected flocks was conducted during the next 12 months. CLINICAL FINDINGS: Of 42 sheep with acute coenurosis that were examined, the most prominent neurological abnormalities were ataxia, depression, blindness, scoliosis, coma and dysmetria. Except for the four sheep that were comatose, all other animals had normal body temperatures and their appetites remained normal or were slightly decreased. Haematological findings of 15 examined sheep were within normal limits. The affected sheep were subject to euthanasia. A histopathological examination was performed in 13 cases. Faecal samples from dogs associated with these flocks were negative for taeniid infections. During the following 12 months cases of chronic coenurosis in these flocks were observed. PATHOLOGICAL FINDINGS: In the 42 animals that were necropsied, the main gross findings were cystic formations between 0.5–1 cm in diameter with translucent walls that were seen lying free on the leptomeninges or partly penetrating the brain tissue, sterile microabscecess and brain necrosis. Histopathological evaluation of tissue sections of 13 brains showed multifocal purulent or pyogranulomatous meningoencephalitis, accompanied by eosinophilic infiltrations. No bacteria were isolated following bacterial culture of brain tissue Parasitological examination of the cysts from five cases revealed whitish specks on the transparent cyst wall and germination membrane representing the scolices. DIAGNOSIS: Acute coenurosis was diagnosed in all cases studied. CLINICAL RELEVANCE: Acute coenurosis can be one of the causes of acute encephalopathy mainly in lambs, but also in adult sheep. This condition is incurable, but can be controlled by changing the feeding regime. Cases of chronic coenurosis may be seen a few months later in the same flock.

Effects of Serum from Neurocysticercosis Patients on the Structure and Viability of Taenia solium Oncospheres

Neurocysticercosis, caused by Taenia solium, is arguably the most common parasitic disease of the central nervous system. In taeniid infections of nonhuman mammals, there is strong evidence of immunity in the intermediate host to the invasive larvae (oncospheres). This immunity, which is mediated by antibody and complement, has been exploited to develop vaccines that effectively prevent infection. To examine the immune response in humans, T. solium eggs were hatched and activated in vitro. Activated oncospheres were incubated with heat-inactivated sera from patients with neurocysticercosis with or without complement (guinea pig serum). Controls included oncospheres plus complement alone, normal human serum alone, normal serum with complement, or buffer alone. Serum from infected patients, especially with complement, markedly reduced oncosphere mobility and led to disappearance of secretory vesicles and loss of membrane integrity. Viability as assessed by staining with dimethyl-thiazolyl-diphenyl-tetrazolium was reduced from 92.5% in controls to 61.5% with immune serum and 38.8% with immune serum and complement (P < 0.01). Preliminary western blot analysis showed antigens at 22, 64, and 70 kDa recognized by all 3 sera, but not by control sera. These data suggest that sera from patients with cysticercosis can kill oncospheres in vitro and may be used to identify protective antigens.

Molecular characterization of the surface and cyst fluid components of Taenia crassiceps

Information relating to the characterization of cestode surface macromolecules is limited. This is especially the case with Taenia crassiceps, a well-recognized model for the study of larval cestodiasis. Here, the protein and glycoprotein composition of the tegumental surface and cyst fluid of the metacestode have been investigated using radio-isotope labelling, immunoprecipitation, SDS-PAGE and lectin affinity chromatography. A restricted number of surface proteins was labelled with the 125I/Iodogen method although the majority were immunogenic; in contrast an array of cyst fluid antigens were labelled. Host serum proteins, including immunoglobulins, were identified on the surface and in the cyst fluid. Some of the 125I-labelled surface proteins, including a 37 kDa molecule, have been shown to be glycoproteins and probably contain-D-mannose and/or D-glucose; there is limited or no N-acetylglucosamine and no terminal galactose present on these components. A 37 kDa surface molecule, possibly the same glycoprotein, was also precipitated by infection sera and this may endorse the theory that highly immunogenic carbohydrates are continuously shed by T. crassiceps as a mechanism for diverting the immune response of the host. Radio-iodinated and biosynthetically labelled T. crassiceps antigens were highly cross-reactive with antibody raised to other cestodes and not one antigen was identified as a possible candidate for use in specific immunodiagnosis of any of the important taeniid infections.

Evaluation of spleen lymphocyte responsiveness to a T-cell mitogen during early infection with larval Taenia taeniaeformis.

The effect of taeniid infection on the in vitro cellular response of the host was investigated. Infections of Taenia taeniaeformis decreased the ability of spleen cells from susceptible C3H/He mice to respond to the T-cell mitogen concanavalin A (Con A) as early as 2 days postinfection (pi) reaching a suppression peak at day 12 pi. Similar experiments performed with spleen cells from infected BALB/c mice, resistant to the infection, revealed little or no suppression of Con A stimulation. The results suggested that susceptibility to the parasite may be due to its ability to induce a partial suppression of the host's immune system. The role of adherent splenocytes from infected C3H/He mice in the production of a deficient response to Con A during early infection was studied by coculturing experiments. These experiments demonstrated that adherent populations from infected mice did not play a direct role in the Con A-suppressor mechanisms. Concomitant with the suppressor activity an increased background proliferation was observed with nonstimulated splenocytes from C3H/He mice infected with T. taeniaeformis. Plasma from infected mice was able to suppress the response of normal spleen cells to Con A and to stimulate a proliferative response in cultured splenocytes from noninfected animals. The results suggest the presence of factors in the plasma of infected mice which may be modulating the immune response to the parasite.